Slack adjusting devices for air brakes



May 29, 1956 J. J. DALY 2,747,700

SLACK ADJUSTING DEVICES FOR AIR BRAKES Filed Sept. 4, 1952 2 Sheets-Sheet 1 May 29, 1956 J. J. DALY sLAcR ADJUSTING DEVICES FOR AIR BRAKES 2 Sheets-Sheet 2 Filed Sept. 4, 1952 United States Patent O SLACK ADJUSTIN G DEVICES FOR AIR BRAKES John J. Daly, Cheyenne, Wyo. Application September 4, 1952, Serial No. 307,850

Claims. (Cl. 18S-196) The invention relates to devices for automatically adj usting the slack in the rigging for operating the brake shoes, or the clearance between the brake shoes and the car wheels, in railway cars.

One object of the invention is to provide an improved slack adjusting device for railway brake systems which will be automatically and pneumatically controlled to compensate for variations in the slack or clearance which results from wear on the brake shoes.

Another object of the invention is to provide an improved slack adjusting device which is mounted on the connecting or tie rod between the brake-operating levers and is effective to shorten the connecting rodV to adjust the levers for taking up slack, and which includes pneumatic means for controlling the adjusting device.

Another object of the invention is to provide a slack adjusting device which is mounted on the connecting rod between the brake operating levers, which is simple in construction and different in operation.

Other objects will appear from the detailed description.

The invention consists in the several novel features which are hereinafter set forth and are more particularly defined by claims at the conclusion hereof.

ln the drawings:

Fig. l is a longitudinal section of an air brake cylinder and the slack adjusting device on the connecting rod between the brake-operating levers, parts being shownY in elevation, the parts being in brake-releasing position;

Fig. 2 is a longitudinal section of the slackadjusting device on the connecting rod between the brake operating levers, the parts being shown in position. assumed when the brakes have been set by an increase of the stroke oi the piston in the brake-operating cylinder, preparatory to shortening of the length of the connecting rod, for adjusting the levers to take up the slack in the connections when the brakes are released;

Fig. 3 is a longitudinal section of the slack-adjusting devicewhen the brake-operating levers have been adjusted to compensate for the slack;

Fig. 4 is a plan view of the air brake cylinder, the slack adjusting device and the brake-operating levers which are shown in brake-releasing position;

Fig. 5 is a section taken on line 5--5 of Fig, 1; and

Fig. 6 is a section taken on line 6.-6 ofj Pig'. l.

The invention is exemplified with an air brake cylinder 10 with a piston 11 slidable therein and liXed to. aV tubular stem 13. A pipe (not shown). delivers air under pressure into and exhausts air from one. end of cylinder 1,0, for imparting outstrokes to the piston 11 for operating the brake system. A spring 14 is adapted to retract the piston 11 for releasing the brakes. The brake rigging includes a floating lever 17, a lever 18. fulcrumed at 16 at one end of cylinder 10, a connecting or tie rod generally designated 19 between levers 17 and 18, and suitable. connections between said levers and all of the. brake shoes on a railway truck. These levers, and their connections with the brake shoes, may be of standard construction, as well understood in the art. The brake shoes are applied by 2,747,700 Patented May 29, 1956 ICC air in cylinder 10 and released during the instroke of piston 11 by spring 14 while air is exhausted from said cylinder. In these brake systems, the piston 11 in cylinder 10 is operable to apply strokes of suicient magnitude to lever 17 to apply the brakes to the car wheels and' to adjust the stroke of lever 17 when slack develops in the brake connections.

In the present invention, the connecting or tie rod` 19 includes elements which are slidably adjustable to vary the length of the rod for adjusting the levers 17' and 18 to take up slack in the brake connections. A thrust sleeve 21 is mounted in the tubular stern 13 and its inner end abuts the piston 11. A stem 22 is slidably mounted in sleeve 20, extends to the outside of sleeve 20, is provided at its outer end with a clevis 23 and its inner end abuts the piston. Lever 17 is pivoted on a pin 24 which is carried on the clevis l23. The brake-operating mechanism is adapted to apply the brake shoes when the connections are in normal condition, or without substantial slack, with a predetermined stroke, usually 8 of the piston 11. During strokes of this length, the connecting rod 19 will operate as` a unit of fixed length between levers 17 and 18. When, as a result of slack, the outstroke of the piston 11 increases a predetermined amount, say to 81/2", the piston 11 opens a port 25 in cylinder for delivering air from cylinder 10 to the pneumatic device, hereinafter described, for controlling the elements of the connecting rod 19 for adjust ing the levers 17 and 18 to take up slack.

The connecting rod 19 and the slack-adjusting device thereon comprises, a rod section 28 which is pivoted at 29 to lever 18, a casing 30, one end of which constitutes an air cylinder 30', a clevis 31 on casing 30 to which lever 17 is pivoted at 32, a hollow plunger 33 slidable in casing 30 and provided at one end with a piston 34, and a stem 35 which is rigid with or welded to rod section 28 and slidably lits in plunger 33. Stem 3S is provided with an elongated series of ratchet teeth 36, which are adapted to be engaged by a series of ratchet teeth 37 on a dog 38 which is mounted for radial sliding movement in an olsetl 39 of casing 30. The teeth 36 and 37 are inclined to the aXis of the teeth on the stem 35 to latch the stem against movement in one direction in the casing 30 and to permit the eiective length of the tie rod to be shortened for moving the pivots 29 and 32 together. This permits the levers 17 and 18 to be relatively positioned for taking, up slack in the brake connections. Dog 3S is pressed into engage,- ment with stern 35 by a spring 40 in oHset 3.9 of casing, 30,v and is provided with a stern 4'1 which is slidable insaid offset and a ring 42 pivoted to stem 4 1 for pulling dog 3,3 away from the ratchet teeth 36 on stern 35 when resetting the stem into its normal position relatively to the casing 30.

A second ratchet device is, provided for shifting the stem in the casing 30 and this comprises a dog 45' which is provided with a tooth 46 and is mounted for radial sliding movement in a socket 47 which is mounted on the hollow plunger 33 and extends through an elongated slot 48 in casing 30. Dog 45' is pressed inwardly to. engage stem 3S by 4a spring 49 in socket 47. A stem 50 is slidable in socket 47 and a ring 51 is pivoted to said stem for disengaging dog 45 from stem 35 when resetting the stem 4 5 relatively to the casing 30. The socket 47 is secured on plunger 33 by lugs 60 which are screwed to said plunger. A spring 54 is interposed between the inner end of plunger 33 and a hard metal ring 55. which is xedly po sitioned in casing 30 by a removable head 56 on said. Casing. Spring 54 urges plunger 33 and piston 34 outward in cylinder 30. A flexible air pipe 56 connects the port 25 in cylinder 10 and the outer end of cylinder 30 in casing 30 in which piston 3.4 is slidable. When air is admitted to cylinder 30 from cylinder 10, the pressure against the outer face of piston 3.4 will shift plunger 3 3, socket 47 and dog 45 one step to the left until dog 45 snaps into engagement with the next succeeding tooth 36 on stem 35, as shown in Fig. 2. When the brakes are released, air will be exhausted from cylinder 30' via pipe 56 and cylinder 1t?. Then spring 54 will shift plunger 33, piston 34 and socket 47 and dog 45 one step in casing 30 to the right. The teeth 36 engaged with the teeth 37 on dog 33 will release dog 38 and permit stem 35 to slide one step to the left in casing 3) into position shown in Fig. 3.

A spring 68 between the inner end of stem 35 and one end of plunger 33 urges sai-d stem so its ratchet teeth 36 will be held against the teeth 37 on dog 38. When the brake connections have been restored to normal conditions to eliminate slack, the dogs 45 and 38 can be disengaged trom the teeth on stem 35. Spring 69 will then shift said stem outwardly in plunger 33 while the dogs are released, until dog 45 engages the innermost tooth on stem 35 for the normal operation of the brake connections without slack.

The operation will be as follows: When the brake connections are in normal condition or -with substantial slack, and air is admitted to cylinder lil for setting the brakes, the piston El will have a stroke of substantially 8 inches so that port 25 will not open to admit air from cylinder 11 to cylinder' 36 on the tie rod 19. Piston 11 will operate stem 22 outwardly until the brakes are set. The pivot pin 32 for lever 17 will exert an outward thrust on casing 3h und the teeth 37 on dog 38 will abut against the teeth 36 on stem 35 and positively shift the tie rod toward the right and operate lever 13 from lever 17. The several parts of the tie rod will be locked for operating the lever 13 toward the right without change in the slackadjusting device. When air is exhausted from cylinder 10, spring 14 will retract piston 11 and sleeve 2t?. Stem 22 will be retracted by the lever 17 when the brake connections are released.

When suicient slack occurs in the brakes or connections, so that the stroke of piston 11 is vincreased from 8 to 81/2 inches, said piston will travel to open port 25 when the brakes are applied. Air then passes from cylinder via pipe 56 into cylinder 30' in casing 30. This exerts an inward pressure on the outer end of piston 34 and shifts plunger 33 one step to the left in casing 30 against the force of spring 54 until socket 45 is arrested by one end of slot 48. This moves the socket 46 and dog 45 one step to the left and said dog snaps over the next tooth adjacent the inner end of stem 35. When air is exhausted from cylinder 10 to release the brakes, it will also be exhausted from cylinder 30 through pipe 56 and the cylinder 10 at the right of piston 11. When the air pressure is exhausted from cylinder 30' and the brakes have been released, spring 35 shifts plunger 33, piston 34, socket 47 and dog 45 longitudinally of casing 30 to slide the stem 35 to the right until the teeth of dog 38 snap into engagement with the next succeeding teeth 36 on stem 35. The length of the tie rod will then be shortcned a distance corresponding to the length of one of the ratchet teeth on the stem 35 and the distance between the pivot 29 of lever 18 and the pivot 32 of lever 17 will be decreased to take up the slack in the brake connections. When the slack has thus been taken up, the brake connections will continue to operate with an 8 stroke of piston 11. When the slack again increases so that the piston 11 will move 81/2 during an outstroke, the operation of plunger 33 and piston 34 and dog 45 repeated as before to again shift stem 35 another step to shorten the length of the tie rod when the brakes are released, for adjusting the levers 17 and 18 to take up the slack. The successive operations of dog 45 act cumulatively to take up slack as it progressively increases. When the brake connections or brake shoes are renewed or replaced, the dogs 38 and 45 are retracted through rings 42 and 51 and the stern 35 is reset so that dog 45 will engage the irst tooth at the inner end of stem 35. The dog 38 will then be released so its teeth will re-engage the teeth 36 on 4 stem 35. During this resetting, the spring 60 will move the stem 35 outwardly in plunger 33 into position for engaging dog 45 with the ratchet tooth at the inner end of stem 35 and expedite the resetting of the stem 35 in casing 30.

The invention exemplifies a slack adjusting device which is embodied in the tie rod or link between a pair of brake-operating levers, which includes ratchet means operable by air from the cylinder iti, is simple in construction, eticient in operation, is readily resettable, and is readily accessible for installation and repair.

The invention is not to be understood as restricted to the details set forth since these may be modified within the scope of the appended claims without departing from the spirit and scope of the invention.

Having thus described my invention what l claim as new and desire to secure by Letters Patent is:

l. A slack adjuster for an air brake system which comprises a tie-connection between said levers ineluding a cylinder having one of its ends pivotally connected to and supported on one of said levers, a hollow piston slidably mounted in said cylinder, a rod-section having one of its ends pivotally connected to the other of said levers, its other end extending into and movable in said hollow piston, and provided with a toothed rack, a springpressed dog mounted in the cylinder of the connection and having one-way sliding engagement with the rack, a second spring-pressed dog mounted on the piston and having one-way toothed engagement with the rack for moving, and movement relatively to, the rack, pneumatic means for shifting the hollow piston with the dog mounted thereon in the cylinder of the tie-connection, and a spring for retracting the hollow pistons and second dog.

2. A slack adjuster for an air brake system which comprises a tie connection between said levers including a cylinder having one of its ends pivotally connected to and supported on one of said levers, a hollow piston slidably mounted in said cylinder, a rod section having one of its ends pivotally connected to the other of said levers, its other end extending into and slidable in said hollow piston, and provided with a toothed rack, a springpressed dog slidably mounted in the cylinder of the connection, a second spring-pressed dog slidably mounted on the piston and having one-way engagement with the rack for shifting, and movement relatively to, the rack, pneumatic means for shifting the hollow piston with the dog mounted in the cylinder of the tie-connection, and a spring for retracting the hollow pistons and second dog.

3. A slack adjuster for an air brake system which comprises a tie connection between said levers including a Acylinder having one of its ends pivotally connected to and supported on one of said levers, a hollow piston slidably mounted in said cylinder, a rod-section having one of its ends pivotally connected to the other of said levers, its other end extending into and slidable in said piston, and provided with a toothed rack, a spring-pressed dog mounted in the cylinder of the connection and having one-way engagement with the rack, a second springpressed dog mounted on the piston and having one-way engagement with the rack for shifting, and movement relatively to, the rack, pneumatic means for shifting the hollow piston with the dog thereon in the cylinder of lthe tie-connection, a spring in the cylinder between it and the hollow piston, and a spring for retracting the hollow pistons and second dog.

4. A slack adjuster for an air brake system which comprises a tie-connection between said levers including a cylinder having one of its ends pivotally connected to and supported on one of said levers, a hollow piston slidably mounted in said cylinder, a rod-section having one of its ends pivotally connected to the other of said levers, its other end extending into and slidable in said piston, and provided with a toothed rack, a spring-pressed dog mounted in the cylinder of the connection and having one-way sliding engagement with the rack, a second spring-pressed dog mounted on the piston and having one-way toothed engagement with the rack for shifting, and movement relatively to, the rack, pneumatic means for shifting the hollow piston with a dog thereon in the cylinder of the tie-connection, and a spring in the cylinder between it and the hollow portion, and a spring in the cylinder for retracting the hollow pistons and second dog.

5. A slack adjuster for an air brake system which comprises a tie-connection between said levers including a cylinder provided with a slot having one of its ends pivotally connected to and supported on one of said levers, a hollow piston slidably mounted in said cylinder, a rod-section having one of its ends pivotally connected to the other of said levers, its other end extending into and movable in said hollow piston, and provided with a toothed rack, a spring-pressed dog slidably mounted in the cylinder of the connection and having one-way sliding engagement with the rack, a second spring-pressed dog mounted on the piston and having one-way engagement with the rack for shifting, and movement relatively to, the rack and extending through said slot, pneumatic means for shifting the hollow piston with the dog thereon in the cylinder of the tie-connection, and a spring for retracting the hollow pistons and second dog.

References Cited in the le of this patent UNITED STATES PATENTS 

